Re: [PATCH v3 11/14] perf/hw_breakpoint: Reduce contention with large number of tasks

+static bool bp_constraints_is_locked(struct perf_event *bp)
+{
+	struct mutex *tsk_mtx = get_task_bps_mutex(bp);
+
+	return percpu_is_write_locked(&bp_cpuinfo_sem) ||
+	       (tsk_mtx ? mutex_is_locked(tsk_mtx) :
+			  percpu_is_read_locked(&bp_cpuinfo_sem));
+}

@@ -426,18 +521,28 @@ static int modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type)
  */
 int dbg_reserve_bp_slot(struct perf_event *bp)
 {
-	if (mutex_is_locked(&nr_bp_mutex))
+	int ret;
+
+	if (bp_constraints_is_locked(bp))
 		return -1;
 
-	return __reserve_bp_slot(bp, bp->attr.bp_type);
+	/* Locks aren't held; disable lockdep assert checking. */
+	lockdep_off();
+	ret = __reserve_bp_slot(bp, bp->attr.bp_type);
+	lockdep_on();
+
+	return ret;
 }
 
 int dbg_release_bp_slot(struct perf_event *bp)
 {
-	if (mutex_is_locked(&nr_bp_mutex))
+	if (bp_constraints_is_locked(bp))
 		return -1;
 
+	/* Locks aren't held; disable lockdep assert checking. */
+	lockdep_off();
 	__release_bp_slot(bp, bp->attr.bp_type);
+	lockdep_on();
 
 	return 0;
 }